The present invention relates to carbon--carbon composites and monomers used in their formation. More particularly, the invention relates to a new family of monomers used in the formation of carbon--carbon composites.
Interest in carbon--carbon composites has grown exponentially in recent years. The combination of high specific strength retention at elevated temperatures and chemical inertness have led to their use in applications such as aircraft brakes, space vehicle heatshields and rocket nozzles.
Although the properties of carbon--carbon composites make them very useful, there are inherent problems with typical precursors such as pitch and many thermoset resins used to fabricate these composites. One of the most severe limitations of the presently used precursors is low char yields during pyrolysis. Typical thermoset precursors yield 50-65 weight percent carbon after pyrolysis. This results in the need for repeated impregnation cycles with resin to achieve a void-free sample.
Another problem with typical thermoset and pitch based carbon precursors arises from the high viscosities and intractable nature of these materials. This often results in poor wetting of the reinforcing fiber and/or the need for higher pressures and temperatures during the impregnation cycles.
Accordingly, it would be a significant advancement in the art to provide a precursor for carbon--carbon composites which had a low viscosity. It would be a further advancement in the art if such a resin had a char yield of greater than about 75%.